This proposal is to request support for a Keystone Symposia meeting entitled ?Imaging[unreadable] Immune Responses?, which will be held in Keystone, Colorado from February 25 ?[unreadable] March 1, 2007. The cellular events leading to host defense and immunopathology are[unreadable] dynamic in nature and involve the migration, transient arrest, and redistribution of[unreadable] various hematopoietic cells types between blood, secondary lymphoid organs, and[unreadable] peripheral tissues. For this reason, a great deal of excitement has been generated by[unreadable] the recent application of miniaturized versions of clinical imaging tools such as PET[unreadable] scanning and MRI, confocal and especially multiphoton microscopy, and luminescence[unreadable] imaging to living animals, permitting direct spatiotemporal analysis of immune cells[unreadable] within complex tissue environments. However, standards for data analysis and[unreadable] interpretation are just emerging, as are improved methods that bridge the resolution and[unreadable] time gaps between the various methods, allowing analyses to begin with initiation of a[unreadable] response and to follow it through to pathogen/tumor clearance or induction of[unreadable] autoimmune pathology. This meeting will bring together experts who will describe[unreadable] ongoing and future applications of these new imaging methods and provide the[unreadable] attendees with an understanding of the new biological paradigms that are emerging from[unreadable] such investigations. Speakers will discuss both basic and clinically-related advances,[unreadable] including cell-cell interactions in the development of humoral and cell-mediated immune[unreadable] responses, the events underlying autoimmune pathology in models of rheumatoid[unreadable] arthritis and diabetes, the trafficking of hematopoietic stem cells following grafting,[unreadable] signaling events in the thymus, bone marrow, and secondary lymphoid tissues, the sites[unreadable] of Treg activity, and the interplay between tumor cell growth and immune cell effector[unreadable] activity following anti-cancer vaccination.